The present invention relates to an improved linear motor which is capable of producing a larger thrust in a particular section than thrust produced during normal linear travel.
The linear motors are, in effect, a linearly-unrolled version of the rotary motors. Among currently-known examples of the linear motors are a linear d.c. motor (monopolar or multipolar), linear synchronous motor, linear induction motor and linear pulse motor. Thrust of the linear motors, corresponding to torque of the rotary motors, generally depends on the structure of the motors.
Of various machines etc. to which the linear motors are applied, some require a sufficiently great thrust and others do not require such a great thrust. Further, some of the former may require a great thrust only for a selected or particular working section, and they have so far employed, over an entire working range, a linear motor capable of producing the required thrust. In cases where the required thrust can not be given via the linear motor alone, an additional drive means has been used, in conjunction with or in place of the linear motor, to produce the great thrust for that particular working section.